Sputtering apparatus and system for sputtering employing same

ABSTRACT

The present invention provides a sputtering apparatus employed for producing an optical disc, for example, wherein a material to be processed by sputtering, such as a disc base plate, is placed in a vacuum chamber having an opening for entrance and exit of the material and a sputtering station, and is transported between the opening and the sputtering station by a rotary arm or arms, in such a manner as to simplify and reduce the size of the vacuum chamber and increase the production quantity per unit time. The present invention also provides an arrangement in which at least two of the sputtering apparatus are arranged in juxtaposition, and the sputtering operation is performed by one of the apparatus during the time when the sputtering operation is completed and the next sputtering operation is not started in the remaining apparatus, so that the equipment common to the respective sputtering apparatus, such as the sputtering power source, may be used so as to simplify the apparatus and increase the production quantity per unit time.

TECHNICAL FIELD

This invention relates to a sputtering apparatus for sputtering a metalmaterial, such as aluminum, on an optical disc base plate for producingan optical disc, and a sputtering system employing the sputteringapparatus.

BACKGROUND ART

There has been proposed an optical disc for recording or reproducingpredetermined information signals, such as audio or video signals. Theoptical disc is constituted by a disc base plate formed of, for example,polycarbonate or acrylic resin and on which pits and grooves are formed,and a metal material, such as aluminum, deposited thereon as areflective film.

Among the techniques of depositing the metal material on the disc baseplate, an evaporation method, an ion plating method, and a sputteringmethod are known.

The evaporation method consists in heating a metal material, acting asan evaporation source, in a vacuum chamber for evaporating the metal anddepositing the metal material on the disc base plate placed in theso-produced metal vapor. Since the processing cannot be started withthis method until the metal material is vaporized sufficiently, aso-called batch system is employed for increasing the quantity of theoptical discs produced for a unit time, according to which pluraloptical discs are produced by one evaporating operation of the metalmaterial with the use of a large-sized vacuum chamber capable ofaccommodating plural optical discs. Thus the apparatus is complicated instructure and increased in size so that restrictions are imposed on thefloor space. In addition, since continuous operation cannot beperformed, it is difficult to shorten the processing time to increasethe production efficiency significantly.

Similarly to the evaporation method, the ion plating method consists invaporizing and ionizing the metal material in a vacuum chambercontaining a gas for electrical discharge, such as argon, under areduced pressure, and applying an electrical field thereto foraccelerating the ionized gas and the ionized metal vapor toward the discbase plate for depositing the metal material on the disc base plate.With this ion plating method, similarly to the above describedevaporation method, the metal vaporizing operation is time-consuming, sothat the batch system needs to be employed for increasing the productionquantity of the optical discs per unit time. Hence, it is difficult toreduce the size of the processing apparatus or to shorten the processingtime.

The sputtering method has advantages that the processing can becompleted in a short time, a continuous processing is possible, and thefilms can be formed on the optical discs under the same conditions, sothat the method is suited to mass production or to production of anumber of different types of the disc base plates.

The sputtering method consists in sealing a gas for electricaldischarge, such as argon, under a reduced pressure, in a vacuum chambercontaining a disc base plate and a metal material, such as aluminumacting as a target, and applying an electrical field to said vacuumchamber for ionizing the gas. The thus-ionized gas bombards the metalmaterial, thereby ejecting atoms or molecules of the metal material, soas to be deposited as a thin film on the disc base plate.

Among the known apparatus for performing the sputtering operation is aso-called load-lock type sputtering apparatus shown for example in FIG.26. This sputtering apparatus includes a vacuum vessel 10i and asputtering station 102 provided above the middle portion of the vacuumvessel 101. An inlet 101a by means of which a disc base plate 103 isintroduced into the vessel 101 and an outlet 101b by means of which thedisc base plate 103 is transported out of the vessel 101 are provided atthe opposite sides of the vessel 101.

This sputtering apparatus also includes a transport device 104 fortransporting disc base plates. The transport apparatus 104 is adaptedfor transporting the disc base plates 103 from outside of the vacuumvessel 101 into the vacuum vessel 101 by means of the inlet 101a andtransporting the disc base plates 103 out of the vacuum vessel 101 byway of the sputtering station 102 and the outlet 101b.

A plurality of opening/closure valves 105 are provided within the vacuumvessel 101. These opening/closure valves 105 are adapted for subdividingthe inside of the vacuum vessel 101 into a plurality of hermeticallysealed cells or chambers along the transport direction of the disc baseplates 103. These opening/closure valves 105 are adapted for maintainingthe portions of the vacuum vessel 101 associated with the sputteringstation 102 in a high vacuum state and are opened or closed with theprogress in the transport operation of the disc base plate 103. In thismanner, the chambers of the vacuum vessel 101 are maintained at apredetermined pressure. That is, the portions of the vacuum vessel 101adjacent to the inlet 101a and the outlet 101b are at a lower vacuum,while the middle sputtering station 102 is at the highest vacuum.

Within the sputtering station 102, a target made of a metallic material106 to be applied to the disc base plate s arranged, and a gas forelectrical discharging is present therein under a high vacuum state. Anelectrical field application apparatus, not shown, for applying anelectrical field, is provided in the sputtering station 102.

With the above sputtering apparatus, the disc base plate 103 istransported from the inlet 101a into the inside of the vacuum vessel 101as far as the position of the sputtering station 102 maintained at thehighest vacuum. The above mentioned sputtering operation is performed atthis position so that a thin metal film is deposited on the disc baseplate 103. This sputtering operation is completed within, for example,two to three seconds. The optical disc, on which the thin film has beenformed, is transported to the portions of the vessel 101 maintained atprogressively lower vacuums and discharged out of the vacuum vessel 101by way of the outlet 101b.

Among the apparatus so far known for performing the sputtering operationon the disc base plates 103 is a apparatus shown in FIGS. 27 and 28. Thesputtering apparatus shown in FIGS. 27 and 28 is provided with atransport table 108 which is rotatably supported in a cylindrical vacuumchamber 107 by a supporting shaft 108a and on which are supported aplurality of disc base plates 103. A circular disc inlet/outlet 107ahaving a diameter slightly larger than the outside diameter of the discbase plate 103 is provided above the upper surface of the vacuum vessel107, while there is also provided a sputtering station 102, similar tothe above described sputtering apparatus, at a position substantiallyfacing the disc inlet/outlet 107a.

The transport table 108 is rotated in a direction shown by an arrow r inFIGS. 27 and 28 about the supporting shaft 108a as the center ofrotation, whereby the disc base plate 103 introduced into the vacuumchamber 107 by way of the disc inlet/outlet 107a is transported to aposition facing the sputtering station 102. The transport table 108 istransiently kept at a standstill at the position facing the sputteringstation 102. While the transport table is at a standstill, thesputtering operation is performed on the disc base plate 103. After theend of the sputtering operation, the transport table 108 is againrotated in a controlled manner for transporting the disc base plate 103to the position facing the disc inlet/outlet 107a.

The disc base plate 103 is placed on a disc supporting table 108b fittedinto a recess formed on the transport table 108. A lid 111 formaintaining the vacuum chamber 107 in a vacuum is provided at the discinlet/outlet 107a.

With the above described sputtering apparatus, the disc inlet/outlet107a is kept closed by at least one of the disc supporting table 108b orthe lid 111 by the operation of thrust shafts 109, 110 projecting fromthe bottom surface into the interior of the vacuum chamber 107. In thismanner, the disc base plate 103 may be transported into and out of thevacuum chamber 107 under a state in which atmospheric air is preventedfrom intruding into the inside of the vacuum chamber 107.

It is noted that, with the sputtering apparatus shown in FIG. 26, evenif the time necessary for the sputtering operation itself could bereduced, the time necessary for the sputtering operation itself could bereduced, the time necessary for the transport operation of the disc baseplate 103 into and out of the sputtering apparatus is s long that it isdifficult to reduce the residence time in the apparatus. On the otherhand, if the residence time is long as compared with the sputteringtime, a large number of disc base plates are caused to dwell in theapparatus thus increasing the size of the apparatus and the floor area.In addition, since the vacuum vessel 101 is increased in space, a largerexhaust pump needs to be used in order to maintain a sufficiently lowvacuum in the vacuum vessel to guarantee satisfactory sputtering, withthe result that the apparatus is necessarily increased in size.

Besides, in the above-described sputtering apparatus, since a pluralityof opening/closure valves are used for maintaining the state of vacuumwithin the vacuum vessel, the apparatus is complicated in structure andhence becomes more difficult to produce, while the maintenance of theapparatus becomes more troublesome due to lowered durability of valvesor the like devices. For example, the above mentioned opening/closurevalves need to be replaced after 100,000 repetitions of theopening/closing operations.

The sputtering apparatus shown in FIGS. 27 and 28 is also inconvenientin that, similarly to the sputtering apparatus shown in FIG. 26, thetime necessary in transporting the disc into and out of the apparatuscannot be reduced without considerable difficulties and the apparatuscannot be reduced in size, while the production costs of the apparatuscannot be lowered.

The present invention has been proposed in view of the above describedstatus of the art, and is aimed at providing a sputtering apparatuswhich is small in size, simplified in structure, easy in production andmaintenance and excellent in production efficiency and with which theproduction quantity per unit time can be expected to be increasedsignificantly.

The present invention also aims at providing a processing system inwhich equipment common to the sputtering apparatus, such as a sputteringpower source unit, can be used to reduce the costs of the apparatus, andin which the production quantity per unit time can be expected to beincreased significantly to increase production efficiency.

SUMMARY OF THE INVENTION

The sputtering apparatus according to the present invention includes avacuum chamber having an opening for entrance and exit of a workpiece tobe processed by sputtering, and a processing section including asputtering station, at least one rotary arm provided in said vacuumchamber and including a rest on the free end of the rotary arm, the restbeing adapted for supporting the workpiece, and transfer means fortransferring the workpiece between said opening and said processingstation by the rotary movement of said rotary arm.

The sputtering system according to the present invention comprises atleast two of the above mentioned sputtering apparatus placed injuxtaposition, wherein, when a sputtering operation is completed and thenext sputtering operation is not started in one of the sputteringapparatus, a sputtering operation is performed in the other sputteringapparatus.

With the sputtering apparatus of the present invention, the material tobe processed by sputtering is placed on a rest at the free end of therotary arm provided in the vacuum chamber, and is transported betweenthe opening in the vacuum chamber and the sputtering station. Thus thenumber of the disc base plates residing in the vacuum chambercorresponds to that of the rotary arms. That is, when only one rotaryarm is provided, only one disc base plate is present in the chamber,thereby significantly shortening the residence time of the disc baseplate in the vacuum chamber. On the other hand, the size of the vacuumchamber corresponding to the rotational range of the rotary armsuffices, thereby reducing the size of the apparatus.

With the sputtering system according to the present invention, at leasttwo sputtering apparatus are placed in juxtaposition and, when asputtering operation is completed and the next sputtering operation isnot started in one of the sputtering apparatus, a sputtering operationis performed in the other sputtering apparatus, so that it cannot occurthat the two sputtering apparatus perform the sputtering operationsimultaneously. Thus the sputtering operation is performed in one of theapparatus during the idle time of the other apparatus when thesputtering operation is not performed. Thus the equipment common to theapparatus such as a sputtering power source or a vacuum meter, may beemployed to increase the production quantity per unit time.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing an optical disc producing apparatusto which the sputtering apparatus according to the present invention isapplied.

FIG. 2 is a longitudinal sectional view of a vacuum chamber of theoptical disc producing apparatus.

FIG. 3 is a transverse sectional view of the vacuum chamber of FIG. 2.

FIG. 4 is a longitudinal sectional view showing the state in which thedisc base plate is charged into the vacuum chamber of the optical discproducing apparatus.

FIG. 5 is a longitudinal sectional view showing the state of completionof charging of the disc base plate into the vacuum chamber of theoptical disc producing apparatus.

FIG. 6 is a longitudinal sectional view showing the state in which thedisc plate has been transported to the sputtering station in the vacuumchamber of the optical disc producing apparatus,

FIG. 7 is a longitudinal sectional view of the vacuum chamber of theoptical disc producing apparatus showing the state of processing of thedisc base plate by sputtering.

FIG. 8 is a longitudinal sectional view of the vacuum chamber of theoptical disc producing apparatus showing the state of completion ofsputtering.

FIG. 9 is a longitudinal sectional view of the vacuum chamber of theoptical disc producing apparatus showing the state of completion of discbase plate transfer to the disc inlet/outlet.

FIG. 10 is a longitudinal sectional view of the vacuum chamber of theoptical disc producing apparatus showing the disc base plate takeoutstate.

FIG. 11 is a transverse sectional view showing a modification of thevacuum chamber of the optical disc producing apparatus, and FIG. 12 is alongitudinal sectional view of the vacuum chamber.

FIG. 13 is a longitudinal sectional view showing a further modificationof the vacuum chamber of the optical disc producing apparatus,

FIG. 14 is a longitudinal sectional view of the vacuum chamber showing amodification of the optical disc producing apparatus and FIG. 15 is atransverse sectional view of the vacuum chamber.

FIG. 16 is a longitudinal sectional view showing the state of chargingof the disc base plate into the vacuum chamber of the modification ofthe optical disc producing apparatus.

FIG. 17 is a longitudinal sectional view showing the state of completionof charging of the disc base plate into the vacuum chamber of theoptical disc producing apparatus.

FIG. 18 is a longitudinal sectional view showing the state in which thedisc base plate has been transferred to the sputtering station in thevacuum chamber of the optical disc producing apparatus.

FIG. 19 is a longitudinal sectional view of the vacuum chamber of theoptical disc producing apparatus showing the state of processing bysputtering of the disc base plate.

FIG. 20 is a longitudinal sectional view of the vacuum chamber of theoptical disc producing apparatus showing the state of completion of thesputtering operation.

FIG. 21 is a longitudinal sectional view of the vacuum chamber of theoptical disc producing apparatus showing the state of termination ofdisc base plate transfer to the disc inlet/outlet.

FIG. 22 is a longitudinal sectional view of the vacuum chamber of theoptical disc producing apparatus showing the state of termination ofdisc base plate transfer to the disc inlet/outlet.

FIG. 23 is a perspective view showing an embodiment of the sputteringsystem according to the present invention, and FIG. 24 is a transversesectional view thereof.

FIG. 25(a) is a timing chart showing a typical sequence of operationsfor sputtering by the sputtering system of the present invention; FIG.25(b) is a timing chart illustrating the operating timing of a vacuumpump; and FIG. 25(c) is a timing chart illustrating the operating timingof the sputtering power source.

FIG. 26 is a transverse sectional view showing a conventional sputteringapparatus.

FIG. 27 is a transverse sectional view showing another conventionalsputtering apparatus and FIG. 28 is a longitudinal sectional viewthereof.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

By referring to the drawings, illustrative embodiments of the presentinvention will be explained in detail.

Meanwhile, the present embodiment is an example in which the sputteringapparatus according to the present invention is applied to an apparatusfor producing an optical disc by depositing a thin film of aluminum orthe like metal on a disc plate of synthetic resin, such as polycarbonateor acrylic resin, by sputtering.

An explanation is first made of an example of an apparatus for producingan optical disc which is provided with a sputtering apparatus in whichtwo rotary arms for transferring the material to be processed betweenthe disc inlet/outlet and the sputtering station are provided at apredetermined distance from each other along the axis of rotation and inwhich the sputtering operation on a disc base plate is performedcontinuously by the transfer operation of the rotary arms.

Referring to FIG. 1, the apparatus for producing the optical disc isprovided with a rectangular housing 1, within which are accommodated avacuum chamber 2 and an exhaust system including a vacuum pump, notshown, provided below the vacuum chamber.

Referring to FIGS. 2 and 3, the vacuum chamber 2 has its insidemaintained at a predetermined degree of vacuum by a vacuum pump. On theupper surface of the vacuum chamber 2, a disc inlet/outlet 3, which isan opening for insertion and discharge of the disc base plate, as theworkpiece to be processed by sputtering and the processed disc baseplate, and a sputtering station 4 for performing the sputteringoperation on the disc base plate, are provided in juxtaposition to eachother.

The disc inlet/outlet 3 is in the form of a circular opening which isslightly larger in diameter than the disc base plate 1 inserted ordischarged by way of the inlet/outlet 3. A disc-shaped lid 5 for openingor closing the disc inlet/outlet 3 is provided on the disc inlet/outlet3. As shown by an arrow A in FIG. 2, the lid 5 is supported by asupporting mechanism, not shown, so that the lid may be brought into andout of contact with the vacuum chamber 2. Thus the lid 5 may be movedtoward the vacuum chamber 2 into pressure contact with the rim of theopening of the disc inlet/outlet 3 to close the inlet/outlet 3 or may bemoved away from the vacuum chamber 2 to open the inlet/outlet 3. Suctionpads 5b are mounted on the surface of the lid 5 facing the discinlet/outlet 3. The disc base plate 1 is drawn by these suction pads 5bso that the disc base plate may be introduced or extracted by means ofthe disc inlet/outlet 3.

As shown in FIG. 4, a sealing member 5a, such as an O-ring, is providedon the rim on the lower surface of the lid 5, so that, when the rim ofthe lid 5 abuts on the rim of the opening of the disc inlet/outlet 3, anair-tight state may be maintained within the vacuum chamber 2.

The sputtering station 4 is provided with a disc processing opening 6similar in contour to the disc inlet/outlet opening 3, and a processingsection 7 mounted on the vacuum chamber 2 for overlaying the opening 6and maintaining an air-tight state within the vacuum chamber 2. A metalplate 8, acting as a target and used for sputtering, is accommodated andsupported within the processing section 7, which is formed as a cylinderclosed at the top. A gas for electrical discharging, such as argon,necessary for sputtering, is used under reduced pressure within theprocessing section 7, to which a predetermined electrical field isapplied.

Within the vacuum chamber 2, there are provided paired first and secondrotary arms 9 and 10 constituting transfer means. These rotary arms 9and 10 are supported at the proximal sides thereof by first and secondrotary shafts 11 and 12 so as to be rotated in the horizontal directionsubstantially normal to the axial direction of the rotary shafts 11 and12. The rotary shafts 11 and 12 are provided at an equal distance fromthe disc inlet/outlet 3 and the sputtering station 4 in opposition toeach other with the axial direction extending substantially vertically.The rotary shafts 11 and 12 are also provided at an equal distance fromthe disc inlet/outlet 3 and the sputtering station 4 in opposition toeach other with the axial direction extending substantially vertically.The rotary shafts 11 and 12 are also projected downwardly of the vacuumchamber 2 by means of through-holes, not shown, provided on the bottomsurface of the vacuum chamber 2, and are rotationally driven at thelower ends thereof by driving devices, not shown, so as to be rotatedabout their axes together with the rotary arms 9 and 10. The rotary arms9 and 10 are spaced apart from each other along the axes of the rotaryshafts 11 and 12, so that the arms 9 and 10, when rotated separately, donot abut one on the other.

A sealing member, such as an O-ring, is provided between each of therotary shafts 11 and 12 and each through-hole to maintain the state ofvacuum in the vacuum chamber 2.

On the upper surfaces of the free ends or distal sides of the rotaryarms 9 and 10, there are formed circular positioning recesses 9a, 10afor supporting the disc plates. Fitted rests 13, 14, adapted forsecuring the center holes of the disc base plates, are fitted in theserecesses 9a, 10a. These rests 13, 14 are formed as discs, each being ofa diameter slightly larger than the disc base plate, and are formed withcentral positioning projections 13a, 14a passed through central chuckingopenings in the disc base plates. Thus, the disc base plates are fittedinto the positioning recesses 9a, 10a and positioned relative to therotary arms 9 and 10, while the disc base plates are secured to therests 13, 14. Thrusting shaft inserting apertures 9b, 10b through whichthe thrusting shafts for thrusting the rests 13 and 14 upwards, areformed centrally in the bottom sections of the positioning recesses 9a,10a. Thus the middle bottom sections of the rests 13, 14, supported onthe rotary arms 9, 10, face toward the lower surfaces of the rotary arms9, 10 by means of the inserting apertures 9b, 10b. When the rotary arms9, 10 are rotated by an angle of, for example, 90°, as shown by an arrow0 in FIG. 3, the rests 13 and 14 are moved between the position belowthe disc inlet/outlet 3 and the position below the sputtering station 4.

On the bottom sides of the vacuum chamber 2, a pair of thrusting devices15, 16, each at the inlet/outlet and the processing opening 6,constituting transfer means, are mounted. The thrusting devices 15, 16support the thrusting shafts 15a, 16a, in substantially an uprightposition, so that the thrusting shafts 15a, 16a are extended into theinside of the vacuum chamber 2 through-holes, not shown, in the bottomsection of the vacuum chamber 2. The thrusting devices 15 and 16 arecontrolled by control means, not shown, so that the thrusting shafts15a, 16a are reciprocated vertically as shown by an arrow B in FIG. 2.When the distal sides of the rotary arms 9, 10 face the discinlet/outlet 3 and the processing opening 6, respectively, the thrustingshafts 15a, 16a are thrusted and protruded by the thrusting devices 15,16 so as to abut at the distal ends thereof on the bottom sections ofthe rests 13, 14 by means of the inserting openings 9b, 10b. When thethrusting shafts 15a, 16a are protruded further, the thrusting shafts15a, 16a shift the rests 13, 14 upwards until the rim of the uppersurfaces of the rests 13, 14 abut on and rest against the rim of theopening of the disc inlet/outlet 3 and the disc processing opening 6.Sealing members 13b, 14b, such as the O-rings, are provided on the rimon the upper sides of the rests 13, 14, so that, when the rim on theupper surfaces of the rests abut on the rim of the opening of the discinlet/outlet 3 and the disc processing opening 6, an air-tight state ismaintained within the vacuum chamber 2 and the sputtering station 4.

With the above described apparatus for producing the optical disc, sincethe disc base plate transfer operation from the disc inlet/outlet 3 andthe disc processing opening 6 is performed by the rotary arms 9, 10,each with the small angle of deviation, the size of the vacuum chamber 2may be correspondingly reduced. Thus the floor space may be reduced,while the capacity of the vacuum chamber 2 may be reduced further. Thecapacity of the vacuum chamber 2 may be reduced, while the vacuumchamber for exhausting the chamber may be reduced in size and thedischarging time may be shortened.

The optical disc is produced by the above described apparatus in thefollowing manner.

First, as shown in FIG. 4, the rests 13, 14 are moved upwards by thethrusting devices 15, 16, as shown by an arrow C therein, so that thedisc inlet/outlet 3 and the disc processing opening 6 are closed by therests 13, 14. The lid 5 is moved away from the vacuum chamber 2 so thatthe upper side of the first rest 13 faces upwards by means of the discinlet/outlet 3. The first disc base plate D₁ is placed on the first rest13, and thus is positioned with respect to the rest 13.

Then, as shown in FIG. 5, the lid 5 is moved down to close the discinlet/outlet 3, at the same time that the vacuum pump is actuated tomaintain a predetermined vacuum within the vacuum chamber 2.

At this time, since the capacity of the vacuum chamber 2 is small in thepresent apparatus, the desired vacuum may be reached instantaneously.

The thrusting shafts 15a, 16a are then receded toward the thrustingdevices 15, 16, as shown by an arrow E in FIG. 5, until the rests 13, 14are placed on the distal sides of the rotary arms 9, 10.

When the rests 13, 14 are placed on the distal sides of the rotary arms9, 10, these rotary arms 9, 10 are then rotated in the direction ofsuperposition, as shown by arrows F and G in FIG. 3. Then, as shown inFIG. 6, the first disc base plate D₁, placed on the first rest 13, ispositioned below the disc processing opening 6, while the second rest 14is positioned below the disc inlet/outlet 3.

When the rests 13, 14 are positioned at the respectively prescribedpositions, the rests 13, 14 are then raised by the thrusting devices 15,16, as shown by an arrow H in FIG. 7, until the disc processing opening6 and the disc inlet/outlet 3 are closed by the rests 13, 14,respectively. At this time, the first disc base plate D₁ faces thesputtering station 4 by means of the disc processing opening 6.

The sputtering operation for the first disc base plate D₁ is nowstarted.

While the sputtering operation is performed on the first disc base plateD₁, the lid 5 is moved away from the vacuum chamber 2 until the upperside of the second rest 14 faces the lower side of the disc inlet/outlet3, and a new second disc plate D₂ is placed and positioned on the uppersurface of the second rest 14. The disc inlet/outlet 3 is then closed bythe lid 5 and the vacuum pump is actuated for maintaining thepredetermined vacuum within the vacuum chamber 2. These operations areterminated substantially simultaneously with termination of thesputtering operation on the first disc base plate D₁.

When the sputtering operation for the first disc base plate D₁ comes toa close, the thrusting shafts 15a, 16a are receded toward the thrustingdevices 15, 16, as shown by an arrow I in FIG. 8, for shifting the rests13, 14 down and placing them on the distal sides of the rotary arms 9,10.

when the rests 13, 14 are placed on the distal sides of the rotary arms9, 10, these rotary arms 9, 10 are turned in the direction ofsuperposition (which is opposite to that of the preceding operation).Thus as shown in FIG. 9, the first disc base plate D₁, placed on thefirst rest 13, and on which the thin film of aluminum has been formed,is positioned below the disc inlet/outlet 3, while the second disc baseplate D₂, placed on the second rest 14, is positioned below the discprocessing opening 6.

When the rests 13, 14 are positioned at the respective predeterminedpositions, the rests 13, 14 are moved upwards by the thrusting devices15, 16, as shown by an arrow J in FIG. 10, until the disc inlet/outlet 3and the disc processing opening 6 are closed by the rests 13, 14. Atthis time, the second disc base plate D₂ faces the sputtering station 4by means of the disc processing opening 6.

The sputtering operation for the second disc base plate D₂ is nowinitiated.

On the other hand, during the time when the sputtering operation isperformed on the second disc base plate D₂, the lid 5 is moved away fromthe vacuum chamber 2, at the disc inlet/outlet side, as explainedpreviously. The first disc base plate D₁, placed on the first rest 13 istaken out of the vacuum chamber 2 by means of the disc inlet/outlet 3,while a new third disc base plate D₃ is placed and positioned on theupper surface of the first rest 13. The disc inlet/outlet 3 is closed bythe cover 5 and the vacuum pump is actuated for maintaining apredetermined degree of vacuum in the vacuum chamber 2. These operationsare terminated substantially simultaneously with termination of thesputtering operation for the second disc base plate D₂.

Thus the optical disc is produced in only six seconds from the time thedisc base plate is introduced into the apparatus until it is taken outafter sputtering. In this manner, with the optical disc producingapparatus of the present invention, the production quantity per unittime may be improved with significant increase in production efficiency.

With the above described optical disc producing apparatus, the rotaryshafts 11, 12 supporting the rotary arms 9, 10 are mounted at apredetermined distance along the axial direction. However, as shown forexample in Figs. 11 and 12, the rotary shafts 17, 18 supporting therotary arms 9, 10 may be provided on the same axis. In this case, one ofthe rotary shafts 17, 18 supporting the rotary arms 9, 10 is extendedtowards the lower side of the vacuum chamber 2 and the other is extendedtowards the upper side of the vacuum chamber 2. With the optical discproducing apparatus of the present embodiment, since two disc baseplates are caused to dwell in the vacuum chamber 2, the vacuum chambermay be reduced in size.

Alternatively, as shown in FIG. 13, one of the rotary shafts 19, 20 maybe in the form of a hollow cylinder into the hollow section of which isfitted the other of the rotary shafts 19, 20. With the optical discapparatus of the present embodiment, the vacuum chamber 2 may be reducedin size, as in the preceding embodiment.

Another embodiment of the optical disc producing apparatus, in whichonly one rotary arm is used for transferring the material to beprocessed between the disc inlet/outlet 3 and the sputtering station 4and in which the sputtering operation is repeatedly performed on thedisc base plate by the transfer operation of the rotary arm, ishereinafter explained.

In the present embodiment, the same components as those of the abovedescribed optical disc producing apparatus are indicated by the samenumerals and the corresponding description is omitted for simplicity.

In the optical disc producing apparatus of the present embodiment, asshown in FIGS. 14 and 15, only one rotary arm 22 for transferring thedisc base plate between the disc inlet/outlet 3 and the sputteringstation within the inside of the vacuum chamber 21 is provided and hasits proximal end bolted to the distal end of a rotary shaft 23 protrudedinto the inside of the vacuum chamber 21, so that the arm may be rotatedwith rotation of the shaft 23 about it axis.

In distinction from the vacuum chamber 2 of the preceding embodiment,the vacuum chamber 21 is formed with a sector-shaped opening with anincluded angle of approximately 90°, as shown by an arrow 0 in FIG. 15,through which the rotary arm 22 is rotated, and a vacuum lid 21a havinga disc inlet/outlet 3 and a disc processing opening 6 is mounted inposition for closing the hollow interior. The capacity of the vacuumchamber 21 is significantly reduced because only one rotary arm 22 isused and the range of rotation of the rotary arm 22 determines thecapacity. For example, the capacity is 5 liters, which is not more thanone fifth that of the vacuum chamber having the rotary table a shown inFIGS. 27 and 28.

A duct 24 connected to a vacuum pump for exhausting the air from thevacuum chamber 21 is provided at the mid portion of the bottom of thevacuum chamber 21. Air exhaust is performed immediately after closure ofthe disc inlet/outlet 3 by the lid 5 at the time of introduction or exitof the disc base plate. Since the duct 24 is provided at the middleposition of the vacuum chamber 21 which is not blocked by the rotary arm22, the inside of the vacuum chamber 21 is exhausted instantaneously toa predetermined degree of vacuum. For example, the air exhaust may becompleted in less than one second.

The rotary arm 22 is disc-shaped at the free end adapted for supportingthe disc base plate, and is tapered toward its proximal end. The freeend of the rotary arm 22 is formed with a positioning recess 22a intowhich fits a rest 13 adapted for securing a centering hole of the discbase plate for positioning and securing the disc base plate. The middleportion of the bottom of the recess 22a is formed with an insertingaperture 22b through which thrusting shafts 25 and 26 are passed forthrusting the rest 13 upwards.

The thrusting shafts 25, 26 are extended into the inside of the vacuumchamber 2 by means of through-holes, not shown, formed in the bottom ofthe vacuum chamber 21 for facing the inlet/outlet 3 and the processingopening 6. Disc-shaped thrusting members 25a and 26a for thrusting therest 13 by way of the thrusting aperture 22b formed in the rotary arm 22are attached to the distal ends of the thrusting shafts 25, 26.

The thrusting shafts 25, 26 are adapted for being reciprocatedvertically by driving means provided with control means, not shown, asshown by an arrow K in FIG. 14. When the distal ends of the rotary arm22 face the disc inlet/outlet 3 and the disc processing opening 6, thethrusting shafts 25, 26 are protruded by the driving device for bringingthe thrusting members 25a and 26a into abutment with the bottom surfacesof the rests 13 by way of the inserting aperture 22b. When the thrustingshafts 25, 26 are thrusted further, the rests 13 are thereby shiftedupwards until the rim of the upper surfaces of the rests 13 abuts therim of the opening of the disc inlet/outlet 3 and that of the discprocessing aperture 6. Since a sealing member 13b such as an O-ring isprovided on the rim of the upper surface of each rest 13, an air-tightstate may be kept in the inside of the vacuum chamber 21 and thesputtering station 4.

The components other than those described above are the same as those ofthe preceding embodiment and the description thereof is omitted forsimplicity.

With the above described optical disc producing apparatus, since thetransfer of the disc base plate between the disc inlet/outlet 3 and thedisc processing opening 6 is performed by the sole rotary arm 22 over asmaller angle of rotation, the vacuum chamber 21 may be further reducedin size and capacity. The floor space may be reduced, and the vacuumpump may be reduced in size, so that the desired vacuum may beestablished instantaneously. Since only the sole rotary arm 22 is used,and the duct 24 is provided at a position not blocked by the arm 22,fluctuations in the vacuum degree within the vacuum chamber 21 may beeliminated.

The process of producing the optical disc by the above describedapparatus is hereinafter explained.

First, as shown in FIG. 16, the thrusting shaft 25 provided for the discinlet/outlet 3 is protruded as shown by an arrow M, thereby shifting therest 13 paced on the rotary arm 22 upwards for closing the discinlet/outlet 3 by the rest 13. The lid 5 is moved upwardly away from thevacuum chamber 21 for facing the upper side of the rest 13 by way of thedisc inlet/outlet 3. The disc base plate D₄ is placed and positioned onthe rest 13.

Then, as shown in FIG. 17, the lid 5 is moved down for closing the discinlet/outlet 3, at the same time that the vacuum pump is actuated formaintaining the predetermined vacuum of the order of, for example,5×10⁻³ Torr within the vacuum chamber 21.

Since the vacuum chamber 21 of the present embodiment is significantlyreduced in capacity, the desired degree of vacuum can be reachedinstantaneously. For example, the time until the desired vacuum isreached is not longer than one second.

The thrusting shaft 25 is then lowered, as shown by an arrow N, in FIG.17, toward the side provided with the vacuum pump, thereby shifting therest 1 down until the rest 13 is placed on the distal end of the rotaryarm 22.

When the rest 13 is placed on the distal end of the rotary arm 22, thearm 22 is rotated toward the sputtering station 4 as shown by an arrowL₁ in FIG. 15. The disc base plate D₄, placed on the rest 13, ispositioned below the disc processing opening 6, as shown in FIG. 18.

When the rest 13 is positioned, the thrusting shaft 26 provided belowthe rest 13 is protruded as shown by an arrow 0 in FIG. 19 for shiftingthe rest 13 upwards for stopping the processing opening 6 by the rest13. The disc base plate D₄ faces the sputtering station 4 by way of theprocessing opening 6.

The sputtering operation for the disc base plate D₄ is initiated. Theoperation comes to a close in, for example, only two seconds.

On completion of the sputtering operation, the thrusting shaft 26 islowered toward the side provided with the vacuum pump, as shown by anarrow P in FIG. 20, until the rest 13 is placed on the distal end of therotary arm 22.

When the rest 13 is placed on the distal end of the rotary arm 22, therotary arm 22 is rotated towards the disc inlet/outlet 3, as shown by anarrow L₂ in FIG. 15. The rest 13 supporting the disc base plate D₄, onwhich the thin aluminum film has been formed, is positioned below thedisc inlet/outlet 3, as shown in FIG. 21.

When the rests 13 are positioned in the prescribed manner, the thrustingshaft 25 is protruded, as shown by an arrow in FIG. 22, for shifting therest 13 upwards for closing the disc inlet/outlet 3 by the rest 13.

The cover 5 is moved away from the vacuum chamber 21, and the disc baseplate D₄, placed on the rest 13, is taken out of the vacuum chamber 21via the disc inlet/outlet 3, while a new disc base plate D₅ ispositioned on the upper surface of the rest

The above described process is repeated sequentially for continuouslysputtering disc base plates.

If the optical disc is produced using the optical disc producingapparatus of the present embodiment, since the vacuum chamber 21 is ofan extremely small size, the time necessary for operations other thansputtering may be shortened for significantly reducing the cycle timeelapsed between charging and exit of the disc base plate into or out ofthe apparatus. As a result, the production quantity per unit time andhence the production efficiency ma be increased significantly.

An embodiment of a sputtering system comprised of two or more juxtaposedoptical disc producing apparatus according to any of the precedingembodiments for performing the random sputtering operation by takingadvantage of the idle time during the sputtering operations in each ofthe optical disc producing apparatus, is hereinafter explained.

In the present embodiment, two of the optical disc producing apparatusaccording to the preceding second embodiment are arranged injuxtaposition.

That is, the sputtering system is constituted by two optical discproducing apparatus 27 and 28 juxtaposed to each other as shown in FIGS.23 and 24 and, during the time interval following the end of sputteringand before the start of next sputtering in the apparatus 27, sputteringis performed in the other apparatus 28.

The operation is explained by referring to a timing chart shown in FIG.25(a). In association with the timing chart, the degree of vacuum andthe sputtering pass in each apparatus are shown in FIGS. 25(b) and (c),respectively.

First, in one of the apparatus, e.g. apparatus 27, the vacuum pump isactuated for establishing a predetermined degree of vacuum in the vacuumchamber 21 (see FIG. 17). This operation is performed within a timeinterval shown by an arrow in FIG. 25(a).

The thrusting shaft 25 at the disc inlet/outlet 3 is then loweredtowards the side provided with the vacuum pump and the rest 13 is placedon the distal end of the rotary arm 22 (see FIG. 17). This operation isperformed within a time interval shown by an arrow b in FIG. 25a.

The rotary arm 22 is then rotated towards the sputtering station 4 andthe disc base plate D₄ is placed below the disc processing opening 6(see FIG. 18). This operation is performed within a time interval shownby an arrow c in FIG. 25a.

The thrusting shaft 26 on the side of the disc processing opening 6 isthen protruded for shifting the rest 13 upwards for thereby closing thedisc processing opening 6 (see FIG. 19). This operation is performedwithin a time interval shown by an arrow d in FIG. 25a. During this timeinterval, the time point at which the desired degree of vacuum isreached, that is the mid point A shown in FIG. 25b, is detected, andsimultaneously, the sputtering power source is turned on, as shown inFIG. 25c, for maintaining a predetermined voltage.

The sputtering operation for the disc base plate D₄ is then performed onthe disc base plate D₄ (see FIG. 19). This operation is performed withina time interval shown by an arrow e in FIG. 25(a). On completion of thesputtering operation, the sputtering power source is turned off to lowerthe voltage.

The thrusting shaft 26 on the side of the disc processing opening 6 islowered toward the side provided with the vacuum pump and the rest 13 isplaced at the distal side of the rotary arm 22 (see FIG. 22). Thisoperation is performed within a time interval shown by an arrow f inFIG. 25(a).

The rotary arm 22 is then rotated toward the disc inlet/outlet 3 and thesputtered disc base plate D₄ is positioned below the disc inlet/outlet 3(see FIG. 21). This operation is performed within a time interval shownby an arrow g in FIG. 25(a).

The thrusting shaft 25 on the side of the disc inlet/outlet 3 is thenprotruded for shifting the rest 13 upwards for thereby closing the discinlet/outlet 3 (see FIG. 22). This operation is performed within a timeinterval shown by an arrow h in FIG. 25(a).

Finally, the lid 5 is moved away from the vacuum chamber 21, and thedisc base plate D₄ is taken out of the vacuum chamber 21 (see FIG. 22).This operation is performed within a time interval shown by an arrow iin FIG. 25(a).

In the other apparatus 28, the above described operation is performedrepeatedly, starting with the operation following the end of sputteringin the apparatus 27, that is, with the operation of shifting thethrusting shaft 26 on the side of the disc processing opening 6 towardthe side provided with the vacuum pump and placing the rest 13 on thedistal end of the rotary arm 22 (the operation shown by an arrow f inFIG. 25(a)).

In the apparatus 28, during the time following the end of the precedingsputtering and before the start of the next sputtering operation, theoperation of preparing for sputtering is completed, that is, the timeshown by the mid point B in FIG. 25(b) is detected and simultaneouslythe sputtering power source is turned on as shown in FIG. 25(c) tomaintain the predetermined voltage. The sputtering operation isperformed during this time.

In the present embodiment, the sputtering operation is performed duringthe time when the disc base plate D₄ sputtered by the apparatus 27 istransported to the disc inlet/outlet 3. However, since the sputteringoperation in the apparatus 28 need only be performed during the timefollowing the end of sputtering apparatus 27 and before the start ofnext sputtering, the sputtering operation in the apparatus 28 may beperformed simultaneously with the end of the sputtering operation in theapparatus 27.

By performing the sputtering operation in a random manner by takingadvantage of the idle time during sputtering operations by the apparatus27 and 28, the devices common to the apparatus 27 and 28, such as thesputtering power source, may be used by both the apparatus as long asthey are not used simultaneously by both the apparatus. In addition,with the above described arrangement, the apparatus 27 and 28 may bereduced further in size and production costs, while they may be drivenseparately from each other such that, even when one of the apparatus ifin trouble or halted transiently for maintenance operations, productionmay be continued without interrupting the production line. By performingthe sputtering operation by the two apparatus 27 and 28 placed injuxtaposition to each other, the production quantity per unit time maybe increased significantly. For example, with the use of a soleapparatus, a cycle time of 6 seconds is necessitated since the disc baseplate introduced at the disc inlet/outlet 3 remains in the apparatusuntil it is taken out, whilst a disc may be produced every 3 seconds bythe present system.

Although two apparatus are used in juxtaposition in the present system,three, four or more apparatus may be placed in juxtaposition to performsputtering on the disc base plates in a random manner, as long as thesputtering operation to be performed by one of the apparatus is notoverlapped with that performed by some other apparatus. Besides,although the optical disc producing apparatus of the second embodimentare placed in juxtaposition, the optical disc producing apparatus of thefirst embodiment may also be arranged in juxtaposition with naturallysimilar effects.

With the sputtering apparatus according to the present invention, thematerial to be processed by sputtering is transported between an inletand a sputtering station of a vacuum chamber by a rotary arm or rotaryarms provided in the vacuum chamber so that the number of the disc baseplates residing in the vacuum chamber corresponds to the number ofrotary arms.

Therefore, by using several rotary arms, the capacity of the vacuumchamber as well as the size of the vacuum pump may be reduced to reducethe size of the apparatus. By using the rotary arm or arms as thetransfer means for transporting the material to be processed bysputtering, the construction of the apparatus may be simplified, whilethe production and maintenance may be facilitated.

By producing the optical disc with the use of the sputtering apparatus,the production quantity per unit time may be increased with improvementin production efficiency.

With the sputtering system according to the present invention, since twoor more apparatus, reduced in size in accordance with the presentinvention, are placed in juxtaposition, and the sputtering operation isperformed in one of the apparatus during the time following the end ofthe sputtering and before the start of next sputtering in the otherapparatus, the equipment common to the apparatus may be used to reducethe production costs of the system. The production quantity per unittime may be increased by several times over that when a sole apparatusis used, with consequent further improvement in production efficiency.

Also, with the sputtering system according to the present invention, therespective apparatus may be driven independently, so that, even when theoperation of one of the apparatus ceases due to the malfunction or formaintenance, the remaining apparatus may remain in operation forrealizing an efficient backup system.

What is claimed is:
 1. A sputtering apparatus comprising:a vacuumchamber having an opening for entrance and exit of a workpiece to beprocessed by sputtering and a processing section including a sputteringstation, a first rotary arm provided in said vacuum chamber andincluding a first rest on the free end of the first rotary arm, saidfirst rest being adapted for supporting the workpiece, and an additionalrotary arm provided at a predetermined distance apart from the firstrotary arm in the rotational direction in the vacuum chamber, saidadditional rotary arm having a second rest on the free end of theadditional rotary arm; transfer means for transferring said workpiecebetween said opening and said processing section by the rotationalmovement of said first and said additional rotary arms while the openingis closed by either said first or said second rest; first lift means forraising or lowering either said first or said second rest in saidopening and second lift means for raising or lowering said first orsecond rest in said sputtering station; and means for rotating saidfirst rotary arm and said additional rotary arm so that, when one of thefirst rotary arm and the additional rotary arm is at said opening insaid vacuum chamber, the other of the first rotary arm and theadditional rotary arm is transferring said workpiece to the processingstation.
 2. The sputter apparatus according to claim 1, characterized inthat said first and said second rests are provided removably on saidfirst rotary arm and said additional rotary arm, respectively.
 3. Thesputtering apparatus according to claim 2, wherein each of said firstand second rests is adapted for closing said opening in said vacuumchamber and a processing opening in said sputtering station when saidfirst and second rests are each raised by a respective one of said firstand second lift means.
 4. The sputtering apparatus according to claim 3,further including means for processing said workpiece by sputteringwhilst the processing opening in said sputtering station is closed byone of said first and second rests.
 5. The sputtering apparatusaccording to claim 1, wherein both said rotary arms are mounted on thesame axis.
 6. A sputtering system comprising two or more juxtaposedsputtering apparatus, each of said apparatus controlled by a common meanand including a vacuum chamber having an opening for entrance and exitof a workpiece to be processed by sputtering, and a processing sectionincluding a sputtering station, at least one rotary arm provided in saidvacuum chamber and having a rest on a free end of the rotary arm, saidrest being adapted for supporting the workpiece, and transfer means fortransferring said workpiece between said opening in said vacuum chamberand said processing section by rotation movement of said rotary arm, andmeans for performing a sputtering operation by one of said apparatuswhile remaining apparatus are not performing a sputtering operation. 7.The sputtering system according to claim 6 wherein the sputteringoperation is performed by one of the apparatus during the time when thesputtering operation is completed and the next sputtering operation isnot started at the remaining sputtering apparatus.
 8. The sputteringsystem according to claim 7 wherein the sputtering operation isperformed by one of the apparatus during the time when the materialprocessed by sputtering by one of the apparatus is transported to saidopening.